A New Cold Stream near the Southern Galactic Pole

TL;DR

This paper reports the discovery of a new, extremely faint, old, and metal-poor stellar stream near the southern Galactic pole, identified using Gaia data, with no known associated clusters or streams.

Contribution

The paper introduces the first detection of the SGP-S cold stellar stream near the southern Galactic pole using Gaia EDR3 data, revealing its properties and uniqueness.

Findings

Stream is at ~9.5 kpc distance

Stream spans 58° by 0.6° on sky

Surface brightness is extremely low at 36.2 mag arcsec$^{-2}

Abstract

We report the discovery of a cold stream near the southern Galactic pole (dubbed as SGP-S) detected in $Gaia$ Early Data Release 3. The stream is at a heliocentric distance of $\sim$ 9.5 kpc and spans nearly 58$^\circ$ by 0.6$^\circ$ on sky. The colour-magnitude diagram of SGP-S indicates an old and metal-poor (age $\sim$ 12 Gyr, [M/H] $\sim$ -2.0 dex) stellar population. The stream's surface brightness reaches an exceedingly low level of $\Sigma_G \simeq$ 36.2 mag arcsec$^{-2}$. Neither extant globular clusters nor other known streams are associated with SGP-S.